Thermal measurement and control are a significant part of mobile platform architecture and operating systems (e.g., Microsoft Windows®, and Linux operating systems). Modern central processing units (“CPUs”), with increasing processor core frequencies and power densities, are rapidly reaching a point in which the CPU performance is limited by the amount of heat that can be extracted from the CPU by cooling technology.
High performance CPUs often integrate an on-die thermal diode that converts junction temperatures to some electric value. External analog-to-digital (“A/D”) devices can be found on several computer platforms, converting the electric value into usable information for temperature control. Due to routing and accuracy limitations, the thermal diode is placed in locations which are not at a hotspot of the CPU. Temperature differences as high as 15 degrees C. have been observed between the diode location and the CPU hotspot. The result is inaccurate temperature reading and discrepancy between the reported value and the actual temperature, affecting both device specification and control. Inaccurate temperature readings result in higher design margins, increased cooling costs, and limited functionality.
Another thermal protection mechanism uses a separate sensor to detect a maximum threshold temperature at the hottest location on the die. Once the threshold is reached, a single trigger occurs and thermal protection is initiated. Other than this single trigger, the sensor provides no other feedback for use in thermal or acoustic management.
If this second sensor is external to the device, the external sensor suffers from latency and accuracy problems resulting from the physical separation of the sensor from the hotspot.
There is a need for improved on-die temperature monitoring to improve performance in a thermally constrained environment.